<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            width: 50px;
            height: 50px;
            background: url(images/bgs.png) no-repeat -159px -51px;
            position: fixed;
            right: 10px;
            top: 40%;
        }
        .erweima {
            position: absolute;
            top: 0;
            left: -150px;
        }
        .box a {
            display: block;
            width: 50px;
            height: 50px;
        }
        .hide {
            display: none;
        }
        .show {
            display: block;
        }        
    </style>
</head>
<body>
    <!-- <script src="common.js"></script> -->
    <div class="box" id="box">
        <div class="erweima hide" id="er">
            <img src="images/456.png" alt=""/>
        </div>
    </div>    
    <script src="js/common.js"></script>
    <script>
        // var box= document.getElementById("box");
        // var er= document.getElementById("er");
        var box = my$("box");
        var er= my$("er");
        box.onmouseover = function(){
            er.className="erweima show";
            // er.className=er.className.replace("hide","show");
        };
        box.onmouseout = function(){
            er.className="erweima hide";
        };
        
    </script>   
</body>
</html>